1. Field of the Invention
This invention relates to methods for detection of impending delivery, particularly impending preterm delivery. In particular, this invention is directed to the determination of impending delivery by detecting an increased level of total fibronectin in cervicovaginal secretion samples.
2. Description of the Prior Art
Determination of impending preterm births is critical for increasing neonatal survival of preterm infants. In particular, preterm neonates account for more than half, and maybe as much as three-quarters of the morbidity and mortality of newborns without congenital anomalies. Although tocolytic agents which can delay delivery were introduced 20 to 30 years ago, there has been only a minor decrease in the incidence of preterm delivery. It has been postulated that the failure to observe a larger reduction in the incidence of preterm births is due to errors in the diagnosis of preterm labor and to the patients' conditions being too advanced for tocolytic agents to successfully delay the birth.
Traditional methods of diagnosis of preterm labor have high false-negative and false-positive error rates [Friedman et al, Am. J. Obstet. Gynecol. 104:544 (1969)]. In addition, traditional methods for determining impending preterm delivery, particularly in patients with clinically intact membranes, may require subjective interpretation, may require sophisticated training or equipment [Garl et al, Obstet. Gynecol. 60:297 (1982)] or may be invasive [Atlay et al, Am. J. Obstet. Gynecol. 108:933 (1970)]. An early, objective biochemical marker which indicated increased risk for preterm delivery was sought.
Although preterm neonates account for the majority of the morbidity and mortality of newborns without congenital anomalies, post-date deliveries (deliveries after the due date of the baby) are also a significant source of morbidity and mortality. An early method of detecting impending delivery could also identify women late in gestation who are about to deliver and thus will not deliver post-date.
Recently, Lockwood et al [New Engl. J. Med., 325:669-674 (1991)] reported that fetal fibronectin in cervical and vaginal secretions indicates pregnancies which are at risk of imminent delivery. The authors postulate that damage to the fetal membranes may release fetal fibronectin into the cervix and vagina, giving rise to the biochemical marker.
Other markers which may be released in women with true threatened pregnancies can be used to screen those women who should be closely monitored and to provide additional information about the stage of the disease.